钻柱涡动理论研究的必由之路——钻井液动力润滑学与钻柱动力学相结合

An inevitable way in drill-string whirling research:combination of drilling fluid power lubrication with drill string dynamics

浸泡在钻井液内的旋转受压钻柱,在屈曲和涡动的作用下,容易发生疲劳断裂和使井眼倾斜。对此现象业界已进行了较深入的研究,但还有一些问题没有解决,如随着井斜角的增加涡动现象减小直至消失的原因、屈曲后的钻柱是否一定与井壁接触、钻柱表面与井壁间是否存在滑动及滑动的影响因素、钻柱的稳定性和偏心率随转速的变化规律等。为了寻求上述问题的研究方法,在介绍钻柱的正弦屈曲和螺旋屈曲、旋转钻柱的最大涡动角速度、旋转钻柱与钻井液的相互作用、旋转钻柱与井壁的碰撞和涡动4方面的研究进展基础上,分析了这些研究方法中存在的问题,提出钻井液动力润滑学与钻柱动力学相结合是钻柱涡动理论研究的必然。

Under the action of buckling and whirling, the compressed rotary drill string immersed in drilling fluid is readily to fatigue fail- ure, which may result in well deviation. This topic has been studied more thoroughly, but many problems remain yet to be resolved. For example, what is the reason that as the deviation angle of a well increases, the whirling phenomenon decreases until disappears, whether the buckled drill string must touch wellbore walls or not, whether there exists sliding between the drill string surface and well bore walls or not, if so, what factors affect the sliding, how the stability of drill string couples with rotary speed, and how the eccen tricity of drill string varies with rotary speed. In order to search for research methods to solve these problems, research advances have been introduced in sinusoidal buckle and helical buckle of the rotary drill string, the maximum whirling angular velocity of rolary drill string, interaction between rotary drill string and drilling fluid, and collision between rotary drill string and wellbore walls. Problems re maining in these research methods were investigated and it was pointed out that the combination of drilling fluid power lubrication with drill string dynamics is an inevitable way in drill-string whirling research.